Project Summary. Diabetic retinopathy (DR) is a common complication of diabetes and is the leading cause of blindness in the working population. Currently, >40% of the patient population fails to respond to gold-standard anti-VEGF direct intraocular injection treatments. New therapies that are superior to or synergistic with current approaches are of great value to patients. Unlike current treatment options, new approaches should be non- invasive (into the eye), affordable, and not reliant on specialized facilities. Our research program seeks to develop small molecule PPAR? agonists as first-in-class treatments for DR. The promise of PPAR? agonism as a novel strategy for treating DR has been confirmed in human clinical trials, wherein Fenofibrate (Feno), a clinically used drug for hyperlipidemia, exhibited robust protective effects against DR and retinal neovascularization (NV) in type 2 diabetic patients. We have determined that the protective effects of Feno are unrelated to its lipid-lowering activity, but rather result from its agonism of PPAR?. Feno however, suffers from poor retinal distribution, low affinity/selectivity for PPAR?, and chemotype related dose-limiting toxicities, all of which will limit its use as a DR therapy. Recently, we have identified a novel class of non-fibrate PPAR? agonists that demonstrate improved potency and selectivity over Feno in vitro and exhibit efficacy in a retinal vascular leakage DR animal model (i.p. administration). All totaled, these data provide proof-of-concept and clearly demonstrate that 1) PPAR? maintains critical roles in the major clinical features of DR and 2) Non-fibrate related PPAR? agonists with improved physicochemical properties and ocular distribution have high promise to become first-in-class therapeutic options for DR. Specific Aims. (1) Structure-based hit to lead optimization of novel PPAR? agonists; (2) Determine the potency and efficacy of newly designed and synthesized analogs; (3) Define the downstream molecular mechanism(s) underlying the protective effects of PPAR? agonism against oxidative stress and inflammation in DR. Study Design. We will leverage in silico PPAR? models developed in our lab to guide the design of improved agonists. Synthesized analogs will be assessed in in vitro biochemical and cellular assays for PPAR? potency, level of agonism, and isoform selectivity. Compounds meeting pre-defined metrics will be advanced to secondary assays to determine anti-angiogenic, anti-oxidative, and neuroprotective effects in vitro. Top compounds will be assessed for efficacy against retinal leukostasis, endothelial impairment, pericyte loss, vascular leakage, visual function, and neuroretinal apoptosis in animal models. Top performing compounds will be utilized for detailed studies to define the downstream molecular mechanisms underlying the protective effects of PPAR? agonism against the major etiological drivers of DR. The research is significant in that it will provide new therapeutic leads and a novel approach for the treatment of DR, thus addressing a pressing global need. The research is innovative in that it seeks to provide small molecule, non-invasive options for ocular conditions typically treated with destructive surgical procedures or intraocular injections of biologics.